• 품질경영학회지
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• 제48권4호
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• pp.597-608
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• 2020

Purpose: The purpose of this paper is to present a probability distribution of the burst pressure of API 5L X65 pipes for the reliability assessment of corroded gas pipelines. Methods: Corrosion is a major cause of weakening the residual strength of the pipe. The mean residual strength on the corrosion defect can be obtained using the burst pressure code. However, in order to obtain the pipe reliability, a probability distribution of the burst pressure should be provided. This study is concerned with estimating the burst pressure distribution using Monte Carlo simulation. A response surface method is employed to represent the distribution parameter as a model of the corrosion defect size. Results: The experimental results suggest that the normal or Weibull distribution should be suitable as the probability distribution of the burst pressure. In particular, it was shown that the probability distribution parameters can be well predicted by using the depth and length of the corrosion defect. Conclusion: Given a corrosion defect on the pipe, its corresponding burst pressure distribution can be provided at instant. Subsequently, a reliability assessment of the pipe is conducted as well.

• 한국인터넷방송통신학회논문지
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• 제24권5호
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• pp.117-122
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• 2024

매우 많은 소프트웨어 결함 예측에 관한 연구들이 수행되었으나, 학습 데이터의 부족으로 이들을 사용하기에 어려움이 있었다. 교차 프로젝트 결함 예측은 이를 해결하기 위한 기법으로 학습 데이터가 충분한 소스 프로젝트의 데이터로 학습한 모델을 타겟 프로젝트의 결함 예측에 사용하는 것이다. 학습을 하기 전에 두 프로젝트간의 데이터 분포차이를 최소화하기 위해 전이학습의 일종인 도메인 적응 기법들을 사용한다. 본 논문은 W-BDA, MEDA를 사용한 새로운 모델들을 제작하여 TCA, BDA를 사용한 기존 모델들과 성능을 비교하였다. 평가 실험 결과 MEDA는 타 모델들에 비해 불규칙적이고 나쁜 성능을 보였지만 BDA는 TCA보다 더 나은 성능을 보였고, W-BDA는 BDA보다 약간 더 좋은 성능을 보였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 추계학술대회 논문집
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• pp.67-68
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• 2012

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제44권2호
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• pp.79-85
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• 2018

Objectives: The aim of this study was to evaluate the effects of herbal extracts on bone regeneration. Two known samples were screened. Materials and Methods: We previously established a rat calvaria defect model using a combination of collagen scaffold and herbal extracts. An 8 mm diameter trephine bur with a low-speed dental hand piece was used to create a circular calvaria defect. The experimental group was divided into 4 classifications: control, collagen matrix, Danshen with collagen, and Ge Gan with collagen. Animals in each group were sacrificed at 4, 6, 8, and 10 weeks after surgery, and bone regeneration ability was evaluated by histological examination. Results: Results revealed that both Danshen and Ge Gan extracts increased bone formation activity when used with collagen matrix. All groups showed almost the same histological findings until 6 weeks. However, after 6 weeks, bone formation activity proceeded differently in each group. In the experimental groups, new bone formation activity was found continuously up to 10 weeks. In the Danshen and Ge Gan groups, grafted materials were still present until 10 weeks after treatment, as evidenced by foreign body reactions showing multinucleated giant cells in chronic inflammatory vascular connective tissue. Conclusion: Histological analyses showed that Danshen and Ge Gan extractions increased bone formation activity when used in conjunction with collagen matrix.

• 경영정보학연구
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• 제14권2호
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• pp.103-115
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• 2012

금융정보시스템의 효율적인 운영을 위해서는 사전 예방관리를 기반으로 한 위험 대처능력의 향상이 매우 중요하다. 위험 대처능력을 향상하기 위해서는 기 발생된 위험에 대한 철저한 이해와 분석 및 대책 수립은 필수적이다. 본 연구에서는 금융정보시스템의 정보계, 계정계, 업무계 및 매매체결시스템에서 발생한 4년 5개월간의 장애 데이터를 도메인, 장애요소, 기간 및 요일, 개발단계 및 장애 원인별로 분류 분석하였다. 분석 결과 장애 데이터가 개발단계, 요일, 그리고 원인 별 특성과 추이를 가지고 있음을 확인 하였으며, 정보시스템 간 업무의 연관성으로 인하여 금융 도메인 전체의 위험관리를 위한 위험예보모델 구축의 필요성이 발견되었다.

• BMB Reports
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• 제46권6호
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• pp.328-333
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• 2013

Many bioactive molecules like recombinant human bone morphogenetic protein 2 (rhBMP-2) have been developed for mineralized bone grafts, for which proper scaffolds are necessary to successfully apply the bioactive molecules. In this study, we tested the osteogenic efficacy of rhBMP-2 produced in-house in combination with gelatin sponge as the scaffold carrier in a rabbit radial defect model. The efficacy of the rhBMP-2 was determined by alkaline phosphatase activity assay of C2C12 cells. Two groups of ten rabbits each were treated with rhBMP-2/gelatin sponge, or gelatin sponge only. At 4 weeks, rhBMP-2/gelatin sponge grafts showed more bone regeneration than gelatin sponge grafts, as determined by X-ray radiography, micro-computed tomography, and histological analyses. At 8 weeks, rhBMP-2/gelatin sponge grafts exerted much stronger osteogenic effects. The study demonstrates the improved osteogenic efficacy of the rhBMP-2/gelatin sponge grafts in a rabbit radial bone defect model acting as a bone-inductive material.

• Journal of Periodontal and Implant Science
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• 제40권4호
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• pp.172-179
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• 2010

Purpose: Accurate and exact measurement is an important factor for generating meaningful results in any properly designed study. If all the participating examiners are able to yield similar results, it will be possible to evaluate the objective results of the study more easily and quickly. The purpose of this study was to evaluate the intra- and inter-examiner reproducibility of histometric measurements in the intrabony periodontal defect model. Methods: One wall intrabony defects were surgically created at the distal aspect of the second and the medial aspect of the fourth mandibular premolars in the right and left jaw quadrants in twenty beagle dogs and the defect sites received the following ${\beta}$-tri calcium phosphate, growth differentiation factor-0, growth differentiation factor-100 and sham surgery. Histometric analysis was performed after 8 weeks. Histometric parameters were recorded and repeated at three months interval by three examiners. Intra- and inter-examiner reproducibility was assessed. Results: Most parameters of all the groups showed high intra- and inter-examiner reproducibility. Parameters including defect height, bone regeneration height, cementum regeneration height, and formation of junctional epithelium yielded interexaminer correlation ${\geq}0.9$. The intra-examiner reproducibility showed a high result, over 0.9. Conclusions: Histometric evaluation of the one-wall intra-alveolar periodontal defect model showed high reproducibility not only for a single given examiner but also among the three examiners.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제34권6호
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• pp.377-383
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• 2012

Purpose: The aim of this study was to evaluate the effect of 4-hexylresorcinol and hydroxyapatite combination graft on bone regeneration in the rabbit calvarial defect model. Methods: Ten New Zealand white rabbits were used for this study. Bilateral round shaped defects (diameter: 8.0 mm) were created on the parietal bone. 4-hexylresorcinol and hydroxyapatite combination graft material was grafted into the right parietal bone defect area (experimental). The left bone defect area was not filled with anything (control). The animals were sacrificed at 4 weeks and 8 weeks after grafting. A micro-computerized tomography of each specimen was taken, and the specimens were stained for histological analysis. Results: The average value of bone mineral density (BMD) and Bone volume (BV) was higher in the experimental group than in the control group at 4 weeks and 8 weeks after surgery. However, the difference was not statistically significant (P>0.05) at 8 weeks after grafting. The BMD and BV in the experimental group at 4 weeks after surgery was significantly higher than those in the control group (P<0.05). Conclusion: 4-hexylresorcinol and hydroxyapatite combination graft material showed higher initial bone formation than the control, however, there was no difference at 8weeks after operation.

• International Journal of Industrial Entomology and Biomaterials
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• 제27권2호
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• pp.303-311
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• 2013

In this study, we compared the efficiency of osteoblast differentiation media (ODM) containing three distinct reagent combinations in osteoblastic differentiation of human bone marrow-derived mesenchymal stem cells (hBMSCs) in monolayer culture. In addition, we analyzed growth and differentiation of hBMSCs on silk scaffolds and examined the bone-forming activity of a nanofibrous silk scaffold in a tibia diaphysis defect model of a rat hind limb with intramedullary nailing. Although all three ODM increased alkaline phosphatase activity to a comparable extent, the ODM containing bone morphogenetic protein-2 (BMP-2) was found to be significantly less effective in promoting mineral deposition than the others. Growth of hBMSCs on sponge-form silk scaffolds was faster than on nanofibrous ones, while osteoblastic differentiation was apparent in the cells grown on either type of scaffold. By contrast, bone formation was observed only at the edge of the nanofibrous scaffold implanted in the tibia diaphysis defect, suggesting that use of the silk scaffold alone is not sufficient for the reconstitution of the long bone defect. Since silk scaffolds can support cell growth and differentiation in vitro, loading MSCs on scaffolds might be necessary to improve the bone-forming activity of the scaffold in the long bone defect model.

• 대한두개안면성형외과학회지
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• 제22권5호
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• pp.260-267
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• 2021

Background: Elastic ear cartilage is a good source of tissue for support or augmentation in plastic and reconstructive surgery. However, the amount of ear cartilage is limited and excessive use of cartilage can cause deformation of the auricular framework. This animal study investigated the potential of periosteal chondrogenesis in an ear cartilage defect model. Methods: Twelve New Zealand white rabbits were used in the present study. Four ear cartilage defects were created in both ears of each rabbit, between the central artery and marginal veins. The defects were covered with perichondrium (group 1), periosteum taken from the calvarium (group 2), or periosteum taken from the tibia (group 3). No coverage was performed in a control group (group 4). All animals were sacrificed 6 weeks later, and the ratio of neo-cartilage to defect size was measured. Results: Significant chondrogenesis occurred only in group 1 (cartilage regeneration ratio: mean±standard deviation, 0.97±0.60), whereas the cartilage regeneration ratio was substantially lower in group 2 (0.10±0.11), group 3 (0.08±0.09), and group 4 (0.08±0.14) (p= 0.004). Instead of chondrogenesis, osteogenesis was observed in the periosteal graft groups. No statistically significant differences were found in the amount of osteogenesis or chondrogenesis between groups 2 and 3. Group 4 showed fibrous tissue accumulation in the defect area. Conclusion: Periosteal grafts showed weak chondrogenic potential in an ear cartilage defect model of rabbits; instead, they exhibited osteogenesis, irrespective of their embryological origin.